What about adding a plugin-outlet to about.hbs ?
{{#if contactInfo}}
<section class='about contact'>
<h3>{{i18n 'about.contact'}}</h3>
<p>{{{contactInfo}}}</p>
</section>
{{/if}}
{{plugin-outlet "after-contactinfo"}}
</div>
</div>
This would allow Admins to enable/disable and enter what they wanted there.